_mb_chr( int $codepoint, "UTF-8"|null $encoding = null ): string|false
- Since
- 7.1.0
- Source
wp-includes/compat.php:141
Compatibility
- WordPress
- since 7.1.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in 1 of the 5 tracked releases, added in 7.1.0, and compiles on PHP 7.4 through 8.6-dev.
Parameters
$codepointint- A Unicode codepoint value, e.g. 128024 for U+1F418 ELEPHANT
$encoding"UTF-8"|nulloptional- Must be 'UTF-8' or null.Default:
null
Return value
string|false- A string containing the requested character, if it can be represented in the specified encoding or false on failure.
Performance profile
How much work a call to _mb_chr() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Trivial
- Scaling
- Constant
- Instructions
- 5–53
- Plugin surface
- None
- Called by
- 1
Touches nothing outside its own arguments.
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 96.
Nothing here hands control to plugin code.
1 place in core call this, so the cost is paid more often than your own code shows.
What one call costs · 5 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost _mb_chr() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 5–17 | none |
is_int($codepoint) | 18–22 | chr() |
is_int($codepoint) | 30–34 | chr(), chr() |
is_int($codepoint) | 41–45 | chr(), chr(), chr() |
is_int($codepoint) && !$codepoint | 49–53 | chr(), chr(), chr(), chr() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 96 instructions, 5–53 executed per call, 10 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Used by · 1
- mb_chr()Compat function to mimic mb_chr().
Source code
function _mb_chr( $codepoint, $encoding = null ) { if ( ! is_int( $codepoint ) || ( isset( $encoding ) && 'UTF-8' !== $encoding ) ) { return false; } // Pre-check to ensure a valid code point. if ( $codepoint < 0 || ( $codepoint >= 0xD800 && $codepoint <= 0xDFFF ) || $codepoint > 0x10FFFF ) { return false; } if ( $codepoint <= 0x7F ) { return chr( $codepoint ); } if ( $codepoint <= 0x7FF ) { $byte1 = chr( ( $codepoint >> 6 ) | 0xC0 ); $byte2 = chr( $codepoint & 0x3F | 0x80 ); return "{$byte1}{$byte2}"; } if ( $codepoint <= 0xFFFF ) { $byte1 = chr( ( $codepoint >> 12 ) | 0xE0 ); $byte2 = chr( ( $codepoint >> 6 ) & 0x3F | 0x80 ); $byte3 = chr( $codepoint & 0x3F | 0x80 ); return "{$byte1}{$byte2}{$byte3}"; } // Any values above U+10FFFF are eliminated above in the pre-check. $byte1 = chr( ( $codepoint >> 18 ) | 0xF0 ); $byte2 = chr( ( $codepoint >> 12 ) & 0x3F | 0x80 ); $byte3 = chr( ( $codepoint >> 6 ) & 0x3F | 0x80 ); $byte4 = chr( $codepoint & 0x3F | 0x80 ); return "{$byte1}{$byte2}{$byte3}{$byte4}";}Changelog
Introduced in 7.1.0.
Signature, return type and hooks compared across 1 parsed release.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
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